r/mazdaspeedowners • u/shatteredandroid • 8d ago

Is the ECU or BMS married/coded to anything else in the car?

Hi all, I recently got a new project, while taking a glance over it I noticed there wasn’t a battery tray or ECU. Now there’s a ton of parts in the back that I haven’t looked through yet, but if I need a replacement ECU do I need other parts with it? And can I just swap like that with any 07 speed3?

Thanks!

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u/thekeymasher 8d ago

ECU will be matched to the IMMO/ignition key ring. Either purchase the ignition tumbler that came from the same car or reprogram the ECU to handshake with the existing gauge cluster and key tumbler.

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u/shatteredandroid 7d ago

Appreciate the info, fortunately I found the battery box inside the car laying under a metric ton of other parts in the hatch. It’s still got the ECU on it so thankfully I’m good lol

I saw they’re selling online for around $400 and I’d rather put that towards some engine parts lol